TECHNICAL FIELD
[0001] The invention belongs to the technical field of catalytic hydrogenation, specifically
relates to a catalyst for liquid phase hydrogenation of acetophenone to produce α-phenylethanol,
and relates to the preparation method and use of the catalyst.
BACKGROUND
[0002] α-Phenylethanol is an important chemical intermediate, which is widely used in industries
such as medicine, perfume manufacturing, cosmetics, food and fine chemical. The existing
methods for synthesizing α-phenylethanol mainly include microbial fermentation method
and acetophenone reduction/catalytic hydrogenation method.
[0003] The microbial fermentation method generally uses phenylalanine and fluorophenylalanine
as raw materials, and produces α-phenylethanol through microbial fermentation transformation.
The raw materials used in the microbial method are expensive and the production cost
is high. Currently, acetophenone hydrogenation method is generally used in the production
of α-phenylethanol in industry. This method has the advantages of low production cost,
less by-products, high product yield and high product purity, and the method is suitable
for large-scale production of α-phenylethanol.
[0004] The acetophenone hydrogenation catalysts mainly include noble metal (such as platinum
and palladium) catalysts, nickel-based catalysts, and copper-based catalysts. Noble
metal catalysts and nickel-based catalysts have high costs, are liable to cause aromatic
ring saturation and phenylethanol hydrogenolysis, and have poor selectivity to α-phenylethanol.
Compared with noble metal catalysts and nickel-based catalysts, when using for acetophenone
hydrogenation reaction, copper-based catalysts have the advantages of high activity,
high selectivity and low cost.
[0005] Catalysts for the hydrogenation of acetophenone to produce α-phenylethanol are reported
in many patent documents. In
CN1557545A, a Ni-Sn-B/SiO
2 catalyst was prepared by impregnation method, after low-temperature calcination,
reduction was performed using KBH
4 as a reducing agent. In the catalytic reaction of the catalyst, the maximum selectivity
to phenylethanol is up to 97.5%, but the interaction force between the active component
Ni and the carrier SiO
2 is weak and the active component Ni is easy to lose.
[0006] US4996374 discloses a Pd-C catalyst, but the stability of the catalyst is poor, and it is necessary
to continuously increase the reaction temperature when recycled.
CN1315226A discloses a reduction treated copper-based catalyst and a method for preparing α-phenylethanol
using the catalyst, but the catalyst requires a liquid phase reduction method to improve
the stability thereof, which is complicated in process and costly.
CN1911883A discloses a method for preparing α-phenylethanol using Raney nickel as a catalyst,
but there is a large amount of aromatic ring hydrogenation product α-cyclohexylethanol
in the acetophenone hydrogenation product, the selectivity to α-phenylethanol is low.
[0007] EP0714877B1 uses carbonates of alkali metal and/or alkaline-earth metal to modify the copper-silicon
catalyst, which significantly inhibits the formation of by-product ethylbenzene. However,
the silicon source is added in the form of fumed silica or diatomaceous earth, which
is detrimental to the enhancement of the interaction between the active component
and the carrier, therefore detrimental to the strength of the catalyst.
[0008] Some silicon sources in the catalyst of
WO2016198379 are added in the form of silica sol during extrusion molding, which cannot effectively
disperse the active component copper. None of the above-mentioned publications mentions
the dispersing and stabilizing effects of the additives on the active components,
the mechanical stability during use and strength after use of the molded catalysts.
[0009] Since the acetophenone hydrogenation process is extremely prone to the side reactions
of α-phenylethanol hydrogenolysis/dehydration to form ethylbenzene/styrene, the reaction
rates of hydrogenolysis and dehydration increase rapidly with the increase of the
reaction temperature. In order to improve the selectivity of the acetophenone hydrogenation
process, the liquid phase hydrogenation reaction at a lower temperature is usually
selected. Therefore, the acetophenone hydrogenation catalyst is required to have good
liquid resistance, weak acidity and good activity at low temperature.
[0010] In the prior art, the copper-based catalysts for liquid phase hydrogenation reaction
are not only subjected to various internal or external forces during storage/charging/reduction/reaction
processes, but also subjected to significant decrease in strength during actual use
due to liquid soaking, swelling and so on, which cause the catalyst to be easily crushed
and powdered in the liquid phase hydrogenation system, threatening the stable operation
of industrial units and affecting the life of the catalyst.
[0011] At present, the copper-based catalysts for acetophenone hydrogenation to produce
α-phenylethanol prepared by the precipitation method usually have problems such as
low dispersity of active component copper, strong acidity and weak interaction between
the carrier and the active component, leading to low conversion rate of acetophenone,
large amount of by-products such as ethylbenzene, poor selectivity to phenylethanol
and poor catalyst strength. Therefore, improving the dispersity of the active component
copper and the mass transfer performance of the catalyst, suppressing the acidity
of the catalyst, and improving the liquid resistance of the catalyst are of great
significance for the preparation of acetophenone hydrogenation catalyst with high
activity, high selectivity and high liquid resistance.
SUMMARY
[0012] The purposes of the present invention is to provide a preparation method of a catalyst
for producing α-phenylethanol by liquid phase hydrogenation of acetophenone, and a
prepared catalyst. The catalyst prepared by the method significantly suppresses side
reactions such as hydrogenolysis, and has high catalyst activity and high selectivity;
at the same time, the catalyst has excellent liquid resistance and has high strength
after reduction and liquid phase hydrogenation reaction.
[0013] To achieve one aspect of the above purposes, the present invention adopts the following
technical solutions:
a preparation method for a hydrogenation catalyst, comprising the following steps:
- (1) adding deionized water, a small molecule alcohol, a Gemini surfactant, and an
organic pore-forming agent to a reactor, followed by adding a silica sol and stirring
the mixture well to prepare an aqueous dispersion of silica sol containing the small
molecule alcohol, the Gemini surfactant and the organic pore-forming agent;
- (2) dissolving a salt of a copper containing compound, a salt of a zinc containing
compound, a salt of a rare-earth metal containing compound and a salt of an alkaline-earth
metal containing compound in water to prepare a solution of mixed salt; dissolving
a silicon containing alkaline precipitant and a silicon free alkaline precipitant
in water to prepare an aqueous solution of alkaline precipitant; adding the solution
of mixed salt and the aqueous solution of alkaline precipitant together to the aqueous
dispersion of silica sol for reaction, with the pH of the reaction system during the
reaction process being controlled at 5.0-9.0, and followed by aging to obtain a slurry;
- (3) filtering and washing the slurry to obtain a filter cake;
- (4) drying, calcining and molding the filter cake to obtain the catalyst.
[0014] In the present invention, step (1) aims at mixing deionized water, a small molecule
alcohol, a Gemini surfactant, an organic pore-forming agent and a silica sol well
to prepare an aqueous dispersion of silica sol containing the small molecule alcohol,
the Gemini surfactant and the organic pore-forming agent, wherein, the organic pore-forming
agent is preferably selected from one or more of PMMA, microcrystalline cellulose
and methyl cellulose; the organic pore-forming agent is added during the preparation
process to reduce the diffusion resistance in the raw materials and the product, and
therefore effectively improve the activity and selectivity of the catalyst.
[0015] According to the preparation method of the present invention, preferably, the particle
size of the organic pore-forming agent is <100 µmm, more preferably 1-80 µm, and still
more preferably 3-30 µm, such as 5, 10, 15, 20, or 25 µm. Keeping the particle size
of the organic pore-forming agent within a suitable range will be conducive to further
improving the diffusion mass transfer effect of the raw materials and the product.
If the particle size is too large, it is not conducive to playing an effective role
in improving the mass transfer performance; if the particle size is too small, it
is not conducive to improving the mass transfer performance too.
[0016] According to the preparation method of the present invention, preferably, the amount
of the organic pore-forming agent accounts for 0.5-20wt%, more preferably 1-10wt%
and still more preferably 2-5wt% of the total weight of the catalyst. Keeping the
amount of organic pore-forming agent in a suitable range will be conducive to minimizing
the impact on the strength of the catalyst on the premise of achieving good mass transfer
performance. If the amount of organic pore-forming agent is too small, it is not conducive
to playing an effective role in improving the mass transfer performance; if the amount
of organic pore-forming agent is too much, the mechanical strength of the catalyst
will be affected.
[0017] In the present invention, the total amount of silicon in the catalyst is introduced
by the silica sol and the silicon containing alkaline precipitant together. Preferably,
the amount of silicon introduced by the silica sol accounts for 30-70wt%, more preferably
35-65wt%, still more preferably 40-60wt%, such as 50wt% of the total amount of silicon
in the catalyst. Studies have found that compared with the use of a single silicon
source, using a highly dispersed silica sol and a silicon containing alkaline precipitant
as a composite silicon source, the prepared catalyst is not only highly active but
also has high strength. Preferably, the silica sol is an alkaline silica sol, and
the pH value is 8.0-10.0.
[0018] In the present invention, the small molecular alcohol refers to an alcohol having
a molecular weight of not more than 400, such as a small molecular saturated monohydric
alcohol having a molecular weight of not more than 400. According to the preparation
method of the present invention, preferably, the mass ratio of the small molecule
alcohol to deionized water is 1:20 to 1:10, such as 1:18, 1:15, or 1:12; further preferably,
the small molecule alcohol in step (1) is one or more of methanol, ethanol, propanol
and butanol.
[0019] In the present invention, the used Gemini surfactant is well known in the art, and
it is a new surfactant that connects two or more traditional surfactant molecules
at a hydrophilic group or near a hydrophilic group through a linking group. The Gemini
surfactant has at least two hydrophobic hydrocarbon chains, two polar head groups
and a linking group; the linking group can be long, short, rigid, flexible, polar
or non-polar; the Gemini surfactant can be divided into anionic-type, cationic-type,
nonionic-type and zwitterionic-type Gemini surfactants depending on whether the polar
head group is cationic, anionic or nonionic; the Gemini surfactant can be divided
into symmetric Gemini surfactant and asymmetric Gemini surfactant based on the bipolar
head group and hydrophobic chain structure. According to the preparation method of
the present invention, preferably, the Gemini surfactant in the step (1) is added
in an amount of 0.1%-1% of the total mass of the deionized water and the small molecule
organic alcohol. The specific type of Gemini surfactant used in the present invention
is not particularly limited. In some preferred embodiments, the Gemini surfactant
is a bromide having a structure of C
m-n-m, wherein m is preferably 12, 14 or 16, and n is preferably 2, 3, 6, 8 or 10. The
used Gemini surfactants can be obtained from the corresponding reagents available
on the market, for example, which can be Gemini surfactants having a structure of
C
16-6-16, C
12-10-12, C
14-8-14, C
12-8-12 or C
14-10-14, or Gemini surfactants having a structure of C
16-2-16, C
12-3-12, C
14-2-14 or C
12-3-12, etc., purchased from Henan Daochun Chemical Co., Ltd.
[0020] Studies have found that in the present invention, by adding Gemini surfactant and
small molecular alcohol to modify the silica sol, the dispersity of the silica sol
is improved, such that the active component copper has higher dispersity, and the
catalyst activity is improved. Meanwhile, the Gemini surfactant can further cooperate
with the organic pore-forming agent to promote the formation of mesoporous structure
and improve the mass transfer performance of the catalyst.
[0021] In the present invention, the precipitant refers to substance that can react with
the metal cation in the solution of mixed salt to form corresponding precipitate.
The purpose of step (2) is to prepare a solution of mixed salt and an aqueous solution
of alkaline precipitant, and add the two together to the aqueous dispersion of silica
sol, so that the mixed salt become corresponding precipitate in the aqueous dispersion
of silica sol containing the organic pore-forming agent. Studies have found that by
dispersing the pore-forming agent in the silica sol in advance, and then forming a
precipitate in the silica sol, it is beneficial to the better dispersion of the pore-forming
agent in the precipitate.
[0022] According to the preparation method of the present invention, preferably, the silicon
containing alkaline precipitant is a water soluble silicate, preferably one or two
of sodium silicate and potassium silicate; the silicon free alkaline precipitant is
one or more of potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium
hydroxide, potassium hydroxide, ammonium carbonate, ammonium bicarbonate, carbamide
and ammonia water.
[0023] Those skilled in the art understand that in the present invention, each metal salt
forming the solution of mixed salt is a soluble salt of the corresponding metal. According
to the preparation method of the present invention, preferably, the salt of the copper
containing compound is one or more of copper nitrate, copper chloride and copper acetate;
the salt of the zinc containing compound is one or more of zinc nitrate, zinc chloride
and zinc acetate; the salt of the rare-earth metal compound is one or more of nitrate,
chloride and acetate; the salt of the alkaline-earth metal compound is one or more
of nitrate, chloride and acetate.
[0024] In the present invention, Zn and Cu can form a "solid solution" during the preparation
process, which can effectively promote the dispersion of the active component copper
in the catalyst; the addition of a rare-earth metal also plays a role in improving
the dispersity of the copper in the catalyst and the stability of the catalyst, preferably,
the rare-earth metal is lanthanum and/or cerium; the addition of an alkaline-earth
metal significantly inhibits the acidity of the catalyst, can effectively inhibit
the formation of ethylbenzene, and improves the reaction selectivity, preferably,
the alkaline-earth metal is one or two or more of magnesium, calcium and barium. Those
skilled in the art understand that each metal component is added in an amount such
that the oxide in the prepared catalyst corresponding to each metal component reaches
its target amount. In some preferred embodiments, based on the total weight of the
catalyst, the prepared catalyst contains 20-65 wt% of copper oxide, 15-50 wt% of silicon
oxide, 2-25 wt% of zinc oxide, 0.1-5 wt% of rare-earth metal oxide and 0.5-15 wt%
of alkaline-earth metal oxide; more preferably, the prepared catalyst contains 40-63
wt% of copper oxide, 20-45 wt% of silicon oxide, 5-20 wt% of zinc oxide, 0.2-3 wt%
of rare-earth metal oxide and 0.5-10wt% of alkaline-earth metal oxide; still more
preferably, the prepared catalyst contains 42-60 wt% of copper oxide, 22-40 wt% of
silicon oxide, 10-18 wt% of zinc oxide, 0.5-2 wt% of rare-earth metal oxide and 1-5
wt% of alkaline-earth metal oxide.
[0025] In step (2), the pH of the reaction system during the reaction process is controlled
to 5.0-9.0, such as 5.5-8.0, and then the system is aged to obtain a slurry; preferably,
the temperature of the reaction process and the aging process is controlled to 60-90
°C, such as 70 or 80 °C. The specific process for forming a precipitate through a
reaction and the precipitate aging process are well known in the art, for example,
the reaction process for forming a precipitate can be completed within 1-3 hours,
and then aging for another 1-3 hours.
[0026] In the present invention, the purpose of step (3) is to filter and wash the slurry
to obtain a filter cake; the filtering and washing processes can all adopt the filtering
and washing processes commonly used in the art, which are all processes commonly used
for treating catalysts in the art. In step (4), the drying, calcining, and molding
processes for the filter cake are also commonly used processes for treating catalysts
in the art; in one embodiment, the calcining temperature is 300-700 °C, such as 400,
500, or 600 °C; the calcining time is 4-12h, such as 6, 8 or 10h; the molding may
be tablet molding and the like.
[0027] To achieve one aspect of the above purposes, the present invention also provides
a catalyst prepared according to the above preparation method.
[0028] According to the preparation method of the present invention, preferably, based on
the total weight of the catalyst, the catalyst includes 20-65 wt% of copper oxide,
15-50 wt% of silicon oxide, 2-25 wt% of zinc oxide, 0.1-5 wt% of rare-earth metal
oxide and 0.5-15 wt% of alkaline-earth metal oxide; more preferably, the catalyst
includes 40-63 wt% of copper oxide, 20-45 wt% of silicon oxide, 5-20 wt% of zinc oxide,
0.2-3 wt% of rare-earth metal oxide and 0.5-10wt% of alkaline-earth metal oxide; still
more preferably, the catalyst includes 42-60 wt%, such as 50 wt% of copper oxide,
22-40 wt%, such as 30 wt% of silicon oxide, 10-18 wt%, such as 15 wt% of zinc oxide,
0.5-2 wt%, such as 1 wt% or 1.5 wt% of rare-earth metal oxide, and 1-5 wt%, such as
2 wt% or 3 wt% of alkaline-earth metal oxide.
[0029] The invention also provides use of the above catalyst in the liquid phase hydrogenation
of acetophenone to produce α-phenylethanol.
[0030] Those skilled in the art understand that the catalyst needs to be reduced and activated
before having corresponding catalytic activity for the hydrogenation of acetophenone
to produce α-phenylethanol.
[0031] In a preferred embodiment, the method for reducing and activating the catalyst according
to the present invention comprises: maintaining a volume space velocity of a mixed
gas of hydrogen and nitrogen of 300-1000 h
-1, and preferably first increasing the temperature of the reactor to 160-180 °C, keeping
the temperature constant for 1-2 h and removing the physical water adsorbed by the
catalyst, and followed by introducing a mixed gas of hydrogen and nitrogen with a
volume fraction of H
2 not more than 10v%, such as (5v% ± 2v%), to pre-reduce the catalyst for at least
0.5h, such as 1h, 1.5h or 2h, followed by gradually increasing the proportion of hydrogen
in the mixed gas of hydrogen and nitrogen, for example, gradually increasing the proportion
of hydrogen to 10v%, 20v%, 50v%, 100v% and controlling the hot spot temperature of
the catalyst bed in this process to be not exceed 220 °C, and finally raising the
temperature to 200-220 °C and reducing in pure hydrogen atmosphere for 2-5h, such
as 3h or 4h, to obtain an activated catalyst.
[0032] In a preferred embodiment, when the obtained reduced catalyst is used for the hydrogenation
of acetophenone to produce α-phenylethanol, the reaction pressure is 2.5-5MPa (relative
pressure), such as 3-5MPa (relative pressure), and the reaction temperature is 70-140
°C, such as 120-140 °C, the H
2/HPA (acetophenone) molar ratio is 2-20:1, such as 5:1, 10:1 or 15:1, and the amount
of the catalyst is 0.2-0.6 g
HPA·g
cat-1·h
-1.
[0033] Compared with the prior art, in the process of the liquid phase hydrogenation of
acetophenone to produce α-phenylethanol using the catalyst prepared by the present
invention, the catalyst has evenly distributed active components, high dispersity
of copper, smooth catalyst pores, weak acidity, excellent activity, excellent selectivity
and excellent mechanical strength.
[0034] In addition, as to the catalyst prepared by the method of the present invention,
the addition of a pore-forming agent can effectively improve the mass transfer performance
of the catalyst and is beneficial to the improvement of the catalyst activity; the
use of a composite silicon source can obtain a catalyst for liquid phase hydrogenation
with high activity and good mechanical strength; the addition of Zn, rare-earth, and
alkaline-earth metals in the catalyst is conducive to improving the dispersity of
the active component Cu, inhibiting the acidity of the catalyst and improving the
activity and selectivity of the catalyst.
EMBODIMENT
[0035] The method of the present invention is described in detail below with reference to
the examples, but the present invention is not limited thereto.
[0036] The side pressure strength of the catalyst was measured using a particle strength
tester, and the used catalyst was immersed and protected with ethylbenzene to prevent
the catalyst from being oxidized. The side pressure strengths of 40 pellets of the
reacted catalyst were measured and the average value was taken.
[0037] The copper ion content in the hydrogenation solution was measured by inductively
coupled plasma-atomic emission spectrometry (ICP).
[0038] Unless otherwise specified, the reagents used below are analytically pure and are
commercially available products.
Example 1
[0039] Into a reactor, 200 g of water, 10 g of methanol, 4.0 g of PMMA with a particle size
of 10-30 µm, and 2.0 g of Gemini surfactant with a structure of C
16-6-16 (purchased from Henan Daochun Chemical Co., Ltd) were added and mixed evenly, and
then 120.0 g of alkaline silica sol with a concentration of 30 wt% and a pH value
of 9 was added and stirred well. 332.2 g of copper nitrate, 73.1 g of zinc nitrate,
21.3 g of lanthanum nitrate, 12.7 g of magnesium nitrate were dissolved in 1.5 kg
of water to prepare an aqueous solution of mixed salt, 113.5 g of sodium silicate
and 142.5 g of sodium carbonate were dissolved in water to prepare a precipitant solution,
the two solutions were heated to 70 °C respectively. The coprecipitation method was
used, the two solutions were added dropwise into the reactor at the same time, and
the temperature in the reactor during the precipitation process was controlled at
70 °C, the pH of the system was controlled at 7.0 and the reaction time was 1h. After
the addition of the two solutions was completed, the pH of the system was adjusted
to > 7.5 using a solution with 10 wt% sodium carbonate, the system was aged at 75
°C for 3h, then filtered, washed, the filter cake was dried at 110 °C for 12h, calcined
at 350 °C for 8h, then mixed with 1.5wt% (powder mass) of graphite and pressed into
a 3 × 3 mm cylinder (3mm in diameter and 3mm in height) catalyst, about 200g of Catalyst
A was obtained. Based on the oxides, the catalyst contains 55% of copper oxide, 30%
of silicon oxide, 10% of zinc oxide, 1% of lanthanum oxide and 4% of magnesium oxide.
[0040] Catalyst reduction: the catalyst A was charged in a fixed-bed hydrogenation reactor,
and the charging amount of the catalyst was 100 ml. The catalyst was reduced under
a mixed gas of nitrogen and hydrogen before use. During the reduction, the volume
space velocity of the mixed gas was maintained at 300h
-1. The temperature of the reactor was first raised to 160 °C and the temperature was
maintained for 2h to remove the physical water adsorbed by the catalyst, and then
a mixed gas of nitrogen and hydrogen with a H
2 volume fraction of 5v% was added to pre-reduce the catalyst for 1h. Then the proportion
of hydrogen in the mixed gas of nitrogen and hydrogen was gradually increased to 10v%,
20v%, 50v% and 100v%, the hot spot temperature of the catalyst bed in this process
was controlled not to exceed 220 °C, finally the temperature was raised to 220 °C
and the catalyst was reduced under a pure hydrogen atmosphere for 3h.
[0041] The hydrogenation raw material was an ethylbenzene solution with 15 wt% acetophenone,
and the reaction was carried out under the conditions of a pressure of 2.5Mpa, a temperature
of 70 °C, a molar ratio of H
2/ketone of 5: 1, and a catalyst throughput of 0.3 g
HPA/g
cat/h. The hydrogenation solution was taken every 24h and the copper ion content in the
hydrogenation solution was measured. After 100 hours of reaction, the catalyst was
removed from the reactor and the catalyst was sieved with a stainless steel sample
sieve with a diameter of 2 mm, and the ratio of the mass of the catalyst particles
with a particle size of <1 mm to the total mass of the catalyst was calculated and
used as the catalyst damage rate. A particle strength tester was used to determine
the side pressure strength of the catalyst after the reaction. The results of the
hydrogenation reaction and the average copper ion content in the hydrogenation solution
are shown in Table 1. See Table 2 for comparison of the catalyst before and after
the reaction.
Example 2
[0042] Into a reactor, 200 g of water, 15 g of ethanol, 6.0 g of microcrystalline cellulose
with a particle size of 5-30 µm, and 0.5 g of Gemini surfactant with a structure of
C
12-10-12 (purchased from Henan Daochun Chemical Co., Ltd.) were added, and then 61.3g of silica
sol with a concentration of 30wt% was added and stirred well. 362.4 g of copper nitrate,
87.7 g of zinc nitrate, 22.7 g of cerium nitrate, 4.21 g of calcium nitrate were dissolved
in 1.45 kg of water to prepare an aqueous solution of mixed salt, 130.5 g of sodium
silicate and 149.0 g of sodium carbonate were dissolved in water to prepare a precipitant
solution. The two solutions were heated to 75 °C respectively. The coprecipitation
method was used, the two solutions were added dropwise into the reactor at the same
time, and the temperature in the reactor during the precipitation process was controlled
at 75 °C, the pH of the system was controlled at 7.2 and the reaction time was 1h.
After the addition of the two solutions was completed, the pH of the system was adjusted
to > 7.5 using a solution with 10 wt% sodium carbonate, the system was aged at 80
°C for 3h, then filtered, washed, the filter cake was dried at 100 °C for 24h, calcined
at 400 °C for 12h, then mixed with 1.0wt% (powder mass) of graphite and pressed into
a 3 × 3mm cylinder (3mm in diameter and 3mm in height) catalyst, about 200g of Catalyst
B was obtained. Based on the oxides, the catalyst contains 60% of copper oxide, 23%
of silicon oxide, 12% of zinc oxide, 0.5% of cerium oxide and 4.5% of calcium oxide.
[0043] For the remaining conditions, refer to Example 1.
Example 3
[0044] Into a reactor, 200 g of water, 10 g of propanol, 10.0 g of methylcellulose with
a particle size of 5-20 µm, and 1.0 g of Gemini surfactant with a structure of C
14-8-14 (purchased from Henan Daochun Chemical Co., Ltd.) were added and mixed evenly, and
then 116.7g of silica sol with a concentration of 30wt% was added and stirred well.
302 g of copper nitrate, 87.7 g of zinc nitrate, 5.0 g of cerium nitrate, 6.8 g of
barium nitrate were dissolved in 1.37 kg of water to prepare an aqueous solution of
mixed salt, 198.7 g of sodium silicate and 93.6 g of sodium carbonate were dissolved
in water to prepare a precipitant solution. The two solutions were heated to 80 °C
respectively. The coprecipitation method was used, the two solutions were added dropwise
into the reactor at the same time, and the temperature in the reactor during the precipitation
process was controlled at 80 °C, the pH of the system was controlled at 8.0 and the
reaction time was 1h. After the addition of the two solutions was completed, the pH
of the system was adjusted to > 7.3 using a solution with 10 wt% sodium carbonate,
the system was aged at 85 °C for 3h, then filtered, washed, the filter cake was dried
at 120 °C for 12h, calcined at 550 °C for 8h, then mixed with 1.2wt% (powder mass)
of graphite and pressed into a 3 × 3mm cylinder (3mm in diameter and 3mm in height)
catalyst, about 200g of Catalyst C was obtained. Based on the oxides, the catalyst
contains 50% of copper oxide, 35% of silicon oxide, 12% of zinc oxide, 1% of cerium
oxide and 2% of barium oxide.
[0045] For the remaining conditions, refer to Example 1.
Example 4
[0046] Into a reactor, 200 g of water, 20 g of butanol, 6.0 g of microcrystalline cellulose
with a particle size of 3-20 µm, and 0.2 g of Gemini surfactant with a structure of
C
12-8-12 (purchased from Henan Daochun Chemical Co., Ltd.) were added and mixed evenly, and
then 105g of silica sol with a concentration of 30wt% was added and stirred well.
271.8 g of copper nitrate, 109.7 g of zinc nitrate, 10.6 g of lanthanum nitrate, 25.3
g of calcium nitrate were dissolved in 1.39 kg of water to prepare an aqueous solution
of mixed salt, 182.1 g of sodium silicate and 105.6 g of sodium carbonate were dissolved
in water to prepare a precipitant solution. The two solutions were heated to 60 °C
respectively. The coprecipitation method was used, the two solutions were added dropwise
into the reactor at the same time, and the temperature in the reactor during the precipitation
process was controlled at 60 °C, the pH of the system was controlled at 6.5 and the
reaction time was 1h. After the addition of the two solutions was completed, the pH
of the system was adjusted to > 7.2 using a solution with 10 wt% sodium carbonate,
the system was aged at 70 °C for 3h, then filtered, washed, the filter cake was dried
at 100 °C for 12h, calcined at 450 °C for 6h, then mixed with 1.0wt% (powder mass)
of graphite and pressed into a 3 × 3mm cylinder (3mm in diameter and 3mm in height)
catalyst, about 200g of Catalyst D was obtained. Based on the oxides, the catalyst
contains 45% of copper oxide, 35% of silicon oxide, 15% of zinc oxide, 2% of lanthanum
oxide and 3% of calcium oxide.
[0047] For the remaining conditions, refer to Example 1.
Example 5
[0048] Into a reactor, 200 g of water, 20 g of ethanol, 10.0 g of PMMA with a particle size
of 10-30 µm, and 1.5 g of Gemini surfactant with a structure of C
14-10-14 (purchased from Henan Daochun Chemical Co., Ltd.) were added and mixed evenly, and
then 177.3g of silica sol with a concentration of 30wt% was added and stirred well.
24.6 g of copper nitrate, 131.6 g of zinc nitrate, 7.97 g of lanthanum nitrate, 31.8
g of magnesium nitrate were dissolved in 1.65 kg of water to prepare an aqueous solution
of mixed salt, 107.8 g of sodium silicate and 128.7 g of sodium carbonate were dissolved
in water to prepare a precipitant solution. The two solutions were heated to 85 °C
respectively. The coprecipitation method was used, the two solutions were added dropwise
into the reactor at the same time, and the temperature in the reactor during the precipitation
process was controlled at 85 °C, the pH of the system was controlled at 7.0 and the
reaction time was 1h. After the addition of the two solutions was completed, the pH
of the system was adjusted to > 7.5 using a solution with 10 wt% sodium carbonate,
the system was aged at 90 °C for 3h, then filtered, washed, the filter cake was dried
at 110 °C for 12h, calcined at 650 °C for 4h, then mixed with 1.2wt% (powder mass)
of graphite and pressed into a 3 × 3mm cylinder (3mm in diameter and 3mm in height)
catalyst, about 200g of Catalyst E was obtained. Based on the oxides, the catalyst
contains 40% of copper oxide, 38% of silicon oxide, 18% of zinc oxide, 1.5% of lanthanum
oxide and 2.5% of calcium oxide.
[0049] For the remaining conditions, refer to Example 1.
Example 6
[0050] Into a reactor, 200 g of water, 15 g of methanol, 4.0 g of methylcellulose with a
particle size of 3-30 µm, and 0.8 g of Gemini surfactant with a structure of C
12-8-12 (purchased from Henan Daochun Chemical Co., Ltd.) were added and mixed evenly, and
then 117.3g of silica sol with a concentration of 30wt% was added and stirred well.
314.1 g of copper nitrate, 73.1 g of zinc nitrate, 5.0 g of cerium nitrate, 17.0 g
of barium nitrate were dissolved in 1.5 kg of water to prepare an aqueous solution
of mixed salt, 136.2 g of sodium silicate and 121.2 g of sodium carbonate were dissolved
in water to prepare a precipitant solution. The two solutions were heated to 65 °C
respectively. The coprecipitation method was used, the two solutions were added dropwise
into the reactor at the same time, and the temperature in the reactor during the precipitation
process was controlled at 65 °C, the pH of the system was controlled at 6.8 and the
reaction time was 1h. After the addition of the two solutions was completed, the pH
of the system was adjusted to > 7.5 using a solution with 10 wt% sodium carbonate,
the system was aged at 70 °C for 3h, then filtered, washed, the filter cake was dried
at 110 °C for 24h, calcined at 450 °C for 8h, then mixed with 1.5wt% (powder mass)
of graphite and pressed into a 3 × 3mm cylinder (3mm in diameter and 3mm in height)
catalyst, about 200g of Catalyst F was obtained. Based on the oxides, the catalyst
contains 52% of copper oxide, 32% of silicon oxide, 10% of zinc oxide, 1% of cerium
oxide and 5% of barium oxide.
[0051] For the remaining conditions, refer to Example 1.
Examples 7-12
[0052]
Example 7 is basically the same as Example 1, except that the Gemini surfactant used
in Example 7 was a Gemini surfactant with a structure of C16-2-16, ethylenebis(hexadecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Example 8 is basically the same as Example 2, except that the Gemini surfactant used
in Example 8 was a Gemini surfactant with a structure of C12-3-12, propylenebis(dodecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Example 9 is basically the same as Example 3, except that the Gemini surfactant used
in Example 9 was a Gemini surfactant with a structure of C14-2-14, ethylenebis(tetradecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Example 10 was basically the same as Example 4, except that the Gemini surfactant
used in Example 10 was a Gemini surfactant with a structure of C12-3-12, propylenebis(dodecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Example 11 is basically the same as Example 5, except that the Gemini surfactant used
in Example 11 was a Gemini surfactant with a structure of C14-2-14, ethylenebis(tetradecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Example 12 is basically the same as Example 6, except that the Gemini surfactant used
in Example 12 was a Gemini surfactant with a structure of C12-3-12, propylenebis(dodecyldimethylammonium bromide) (purchased from Henan Daochun Chemical
Co., Ltd.).
Comparative Example 1
[0053] 200 g of water was added to a reactor, and 60 g of fumed silica was added, and the
mixture was stirred well. 332.2 g of copper nitrate was dissolved in 1.5 kg of water
to prepare an aqueous solution of mixed salt, and an aqueous solution with 10 wt%
sodium carbonate was prepared as a precipitant, and the two solutions were heated
to 65 °C respectively. The coprecipitation method was used, the two solutions were
added dropwise into the reactor at the same time, and the temperature in the reactor
during the precipitation process was controlled at 65 °C, the pH of the system was
controlled at 7.0 and the reaction time was 1h. After the addition was completed,
the system was aged at 70 °C for 3h, then filtered, washed, the filter cake was dried
at 110 °C for 24h, calcined at 450 °C for 8h, then mixed with 1.2wt% (powder mass)
of graphite and pressed into a 3 × 3mm cylinder (3mm in diameter and 3mm in height)
catalyst, about 170g of Catalyst G was obtained.
[0054] For the remaining conditions, refer to Example 1.
Comparative Example 2
[0055] 332.2 g of copper nitrate and 292.4 g of zinc nitrate were dissolved in 1.65 kg of
water to prepare an aqueous solution of mixed salt, sodium carbonate was dissolved
in water to prepare an aqueous solution with 10 wt% sodium carbonate, and the two
solutions were heated to 65 °C respectively. The coprecipitation method was used,
the two solutions were added dropwise into the reactor at the same time, and the temperature
in the reactor during the precipitation process was controlled at 65 °C, the pH for
precipitation was controlled at 7.0. After the precipitation was completed, the system
was aged at 70 °C for 3h. After filtration and washing, 10.0g of alumina was added
to the filter cake, the treated filtered cake was dried at 110 °C for 12h, calcined
at 350 °C for 4h, then mixed with 1.5wt% (powder mass) of graphite, pressed and molded
into a 3 × 3mm cylinder (3mm in diameter and 3mm in height) catalyst, about 190g of
Catalyst H was obtained.
[0056] For the remaining conditions, refer to Example 1.
Comparative Example 3
[0057] During the preparation of the catalyst, no small molecular alcohol and Gemini surfactant
were added, and the remaining conditions were the same as in Example 1. About 200
g of Catalyst I was obtained.
[0058] For the remaining conditions, refer to Example 1.
Comparative Example 4
[0059] During the preparation of the catalyst, no organic pore-forming agent PMMA was added,
and the remaining conditions were the same as in Example 1. About 200 g of Catalyst
J was obtained.
[0060] For the remaining conditions, refer to Example 1.
[0061] The results of the hydrogenation reaction of the catalysts of Examples 1-6 and the
average copper ion contents in the hydrogenation solution are shown in Table 1, and
the comparison of the catalysts before and after the reaction are shown in Table 2.
The experimental results of the catalysts prepared in Examples 7-12 are basically
the same as the corresponding experimental results of Examples 1-6 in sequence, in
which the conversion rate of acetophenone were at least 98.1%, and the selectivity
to α-phenylethanol were all at least 99.3%, the detection results of the average copper
ion content in the hydrogenation solution were "not detected"; the side pressure strength
of the catalysts before the reaction were all at least 188 N/particle, and the side
pressure strength of the catalysts after the reaction were all at least 48.5 N/particle.
The catalysts after the reaction were all complete without powdering and crushing.
Table 1 The results of the hydrogenation reaction and average copper ion content in
the
hydrogenation solution
|
conversion rate of acetophenone % |
selectivity to α-phenylethanol % |
average copper ion content in the hydrogenation solution µg/g |
Catalyst A |
98. 1 |
99.4 |
Not detected |
Catalyst B |
99.3 |
99.3 |
Not detected |
Catalyst C |
98. 8 |
99.4 |
Not detected |
Catalyst D |
98.9 |
99.5 |
Not detected |
Catalyst E |
98.6 |
99.3 |
Not detected |
Catalyst F |
99.2 |
99.5 |
Not detected |
Catalyst G |
86.0 |
97.5 |
38.2 |
Catalyst H |
82.1 |
97.6 |
60.8 |
Catalyst I |
92.6 |
98.7 |
Not detected |
Catalyst J |
93.1 |
98.5 |
Not detected |
Note: "Not detected" means the average copper ion content in the hydrogenation solution
is < 0.1 µg/g |
Table 2 Comparison of the catalyst before and after the reaction
|
catalyst before the reaction side pressure strength N/particle* |
catalyst after the reaction side pressure strength N/particle |
catalyst after the reaction state |
Catalyst A |
188.1 |
48.5 |
complete |
Catalyst B |
210.9 |
65.9 |
complete |
Catalyst C |
220.6 |
68.1 |
complete |
Catalyst D |
192.3 |
54.4 |
complete |
Catalyst E |
205.7 |
62.3 |
complete |
Catalyst F |
198.3 |
58.9 |
complete |
Catalyst G |
163.2 |
15.7 |
crushed |
Catalyst H |
106.7 |
could not be tested |
powdered |
Catalyst I |
195.7 |
55.3 |
complete |
Catalyst J |
198.2 |
58.5 |
complete |
* N/particle is the unit of catalyst strength, which is the force applied for 1 catalyst
to crush |
[0062] As can be seen from Tables 1 and 2, when using catalysts A to F, and catalysts I
and J, no copper was detected in the hydrogenation solution, and the catalysts were
complete and the side pressure strength of the catalysts were at least 30 N/particle
after the reaction; however, as to the catalysts of Comparative Example 1 and Comparative
Example 2, after the reaction, the catalysts were severely crushed and the side pressure
strength of the catalysts were low. The catalyst H was powdered so that its side pressure
strength could not be tested. ICP analysis showed that the copper content in the hydrogenation
solution of the catalysts were high, indicating that the catalysts had significant
loss. In addition, catalysts A to F have high activity and can effectively suppress
side reactions such as hydrogenolysis to produce ethylbenzene and dehydration to produce
styrene, and the catalysts of Comparative Examples 1 to 4 not only have low activity
but also poor selectivity.
1. A preparation method for a hydrogenation catalyst, comprising the following steps:
(1) adding water, a small molecule alcohol, a Gemini surfactant and an organic pore-forming
agent to a reactor, followed by adding a silica sol and stirring the mixture well
to prepare an aqueous dispersion of silica sol containing the small molecule alcohol,
the Gemini surfactant and the organic pore-forming agent;
(2) dissolving a salt of a copper containing compound, a salt of a zinc containing
compound, a salt of a rare-earth metal containing compound and a salt of an alkaline-earth
metal containing compound in water to prepare a solution of mixed salt; dissolving
a silicon containing alkaline precipitant and a silicon free alkaline precipitant
in water to prepare an aqueous solution of alkaline precipitant; adding the solution
of mixed salt and the aqueous solution of alkaline precipitant together to the aqueous
dispersion of silica sol for reaction, with the pH of the reaction system during the
reaction process being controlled at 5.0-9.0, and followed by aging to obtain a slurry;
(3) filtering and washing the slurry to obtain a filter cake;
(4) drying, calcining and molding the filter cake to obtain the catalyst.
2. The preparation method according to claim 1, wherein the total amount of silicon in
the catalyst is introduced together by the silica sol and the silicon containing alkaline
precipitant, and the amount of silicon introduced by the silica sol accounts for 30-70
wt%, preferably 35-65 wt%, and more preferably 40-60 wt% of the total amount of silicon
in the catalyst;
preferably, the silica sol is an alkaline silica sol, with a pH value of 8.0-10.0.
3. The preparation method according to claim 1 or 2, wherein the silicon containing alkaline
precipitant is a water soluble silicate, preferably one or two of sodium silicate
and potassium silicate;
the silicon free alkaline precipitant is one or more of potassium carbonate, sodium
bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, ammonium
carbonate, ammonium bicarbonate, carbamide and ammonia water.
4. The preparation method according to any one of claims 1-3, wherein the particle size
of the organic pore-forming agent is <100 µmm, preferably 1-80 µm, more preferably
3-30 µm;
preferably, the organic pore-forming agent is one or more of PMMA, microcrystalline
cellulose and methyl cellulose.
5. The preparation method according to any one of claims 1-4, wherein the amount of the
organic pore-forming agent accounts for 0.5-20wt%, preferably 1-10wt%, more preferably
2-5wt% of the total weight of the catalyst.
6. The preparation method according to any one of claims 1-5, wherein in step (1), the
mass ratio of the small molecule alcohol to water is 1:20 to 1:10; preferably, the
small molecule alcohol in step (1) is one or more of methanol, ethanol, propanol and
butanol.
7. The preparation method according to any one of claims 1-6, wherein the Gemini surfactant
in the step (1) is added in an amount of 0.1%-1% of the total mass of the water and
the small molecular alcohol; preferably, the Gemini surfactant is a bromide having
a structure of Cm-n-m, wherein m is 12, 14, or 16, and n is 2, 3, 6, 8, or 10.
8. The preparation method according to any one of claims 1-7, wherein the rare-earth
metal is lanthanum and/or cerium; the alkaline-earth metal is one or two or more of
magnesium, calcium and barium;
preferably, the salt of the copper containing compound is one or more of copper nitrate,
copper chloride and copper acetate; the salt of the zinc containing compound is one
or more of zinc nitrate, zinc chloride and zinc acetate; the salt of the rare-earth
metal compound is one or more of nitrate, chloride and acetate; the salt of alkaline-earth
metal compound is one or more of nitrate, chloride and acetate.
9. The preparation method according to any one of claims 1-8, wherein the temperature
of the reaction process and the aging process in step (2) is 60-90 °C;
in step (4), the calcining temperature is 300-700 °C and the calcining time is 4-12h.
10. The catalyst prepared by the preparation method according to any one of claims 1-9;
preferably, based on the total weight of the catalyst, the prepared catalyst contains
20-65 wt% of copper oxide, 15-50 wt% of silicon oxide, 2-25wt% of zinc oxide, 0.1-5wt%
of rare-earth metal oxide and 0.5-15wt% of alkaline-earth metal oxide;
more preferably, the prepared catalyst contains 40-63 wt% of copper oxide, 20-45 wt%
of silicon oxide, 5-20 wt% of zinc oxide, 0.2-3 wt% of rare-earth metal oxide and
0.5-10 wt% of alkaline-earth metal oxide;
still more preferably, the prepared catalyst contains 42-60 wt% of copper oxide, 22-40
wt% of silicon oxide, 10-18 wt% of zinc oxide, 0.5-2 wt% of rare-earth metal oxide
and 1-5 wt% of alkaline-earth metal oxide.
11. Use of the catalyst prepared by the preparation method according to any one of claims
1-9 in the liquid phase hydrogenation of acetophenone to produce α-phenylethanol.
12. The use according to claim 11, wherein before catalyzing the hydrogenation of acetophenone
to produce α-phenylethanol, the catalyst is reduced and activated;
preferably, the reduction and activation of the catalyst includes the following steps:
introducing a mixed gas of hydrogen and nitrogen with a volume fraction of H2 not more than 10v% while maintaining the volume space velocity of the mixed gas of
hydrogen and nitrogen to be 300-1000 h-1 to pre-reduce the catalyst for at least 0.5 h, followed by gradually increasing the
proportion of hydrogen in mixed gas of hydrogen and nitrogen and controlling the hot
spot temperature of the catalyst bed in this process to not exceed 220 °C, and finally
raising the temperature to 200-220 °C and reducing in a pure hydrogen atmosphere for
2-5 h to obtain an activated catalyst;
preferably, the process conditions for the hydrogenation of acetophenone to produce
α-phenylethanol using the obtained activated catalyst include: a reaction pressure
of 2.5-5 MPa, a reaction temperature of 70-140 °C, a H2/HPA molar ratio of 2-20:1 and a catalyst amount of 0.2-0.6 gHPA·gcat-1·h-1.